The conversion of a carboxamide substrate to a thiocarboxamide product using conventional thionating agents (e.g., P4S10, Lawesson's Reagent) may be hindered by the presence of heteroatoms in the carboxamide substrate.
By way of example, in the presence of a conventional thionating agent, a heterocyclic carboxamide substrate containing one or more nitrogen heteroatoms (e.g., a carboxamide-substituted piperdine and/or the like) may undergo dehydrogenation to form a pyridinyl material rather than the desired thionated product. As a result, circuitous synthetic pathways that involve the preparation of synthetic intermediates (e.g., cyano compounds), protection-deprotection sequences, and/or the like may be required to effect the desired conversion of a carboxamide substrate to a thiocarboxamide product.